Telegraph system



M 1932. B. P. HAMILTON 19s5z,o1

, TELEGRAPH SYSTEM Filed June 12. 1931 2 Sheets- Sheet '1 mvsmoa ATTORNEY April 5, 1932- B. P. HAMILTON 1,852,050

TELEGRAPH SYSTEM Filed June 12, 1931 2 Sheets-Sheet 2 INVENTOR BY IZ ATTORNEY Patent d pr. 5, 1932 UNITED STATES PATENT oer-flea BAX'I'EB P. HAMILTON, OF RIVER EDGE, NEW JERSEY, ASSIGNOR TO AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK rnnaemn snzs'rnmv Application filed June 12,

This .invention relates totelegraph systems, and more particularly to im rovements in the terminal arrangements telegraph systems utilizin a plurality of carrier or ra- 6 dio frequency c annels for the transmission of messages. v Telegraph systems utilizing either radio or wired facilities usually terminate in loop circuits at each end of the line or at interme- 1 diate repeater points and these loop circuits cuits of which no sending, receiving or reak relays will be needed. The elimination of a large number of telegraph relays from a telegraph .s stem would result in reduced expense an maintainence and impi oved transmission. For example, in certam types of carrier telegraph systems there would be employed three relays at each terminal and six at each intermediate repeating point so that in a three-section telegraph circuit of this type there might be a total of eighteen relays. The arrangements of the invention might eliminate all of such relays. Other objects and features ofthe invention will appear more fully from the detailed description thereof hereinafter given.

In the arrangements of the invention the output of a carrier telegraph detector is passed directly to the loop circuit and operates sensitive relay at the subscribers oflice. This eliminates the need for the receiving relay now used at the channel terminal for repeating signals from the line to the subscribers loop circuit. For sending purposes a resistance network is provided so that when the telegraph key or printer transmitter at the subscribers oflice is open. a comparatively high negative potential is applied to the grid of the sending amplifier tube and this stops the flow of carrier current to the line. When the telegraph key closes the loop circuit positive battery from the loop is applied to the resistance network so as to bring the grid potential of the tube to'the proper value as an amplifier and carrier current is transmitted to that line. This arrangement eliminates the 1931. Serial No. 543,916.

will send a steady spacing signal to the line fegardless of. any incoming signals from the The invention may be more fully under-' stood from the following description together with the accompanying drawings in the Fi ures 1-4 of which the invention is illustrate Figs. 1 and 2 illustrate the invention as applied to terminal loop circuits for half and full duplex systems, respectively. Similar reference characters have been used to denote like parts in both of these figures. Figs. 3 and 4 illustrate the invention as applied to intermediate repeater arrangements for half and full duplex systems. Similar reference characters have been used to denote like parts in Figs. 3 to 4.

In Fig. 1 the arrangements of the invention are shown as applied to a half duplex carrier telegraph system. The telegraph line is shown as L Connected thereto would be a circuit 1 terminating .in a transformer to which might be connected a plurality of incoming and outgoing carrier telegraph circuits. The outgoing circuits are shown as L and L and-would include therein selective circuits, such as filters or tuned circuits SF and 'SF respectively. The incoming circuits are shown as L and L and would include therein selective circuits, such as filters or tuned circuits RF and RF respectively. The incoming circuits, such as L are con.- nected to amplifiers anddetectors, such as 4 and 5. The output of detector 5 is passed directly to a sensitive relay, such as 8, atthe subscribers oifice by way of the loop circuit 6 and operates such relay. This eliminates the receiving relay heretofore used at the carrier channel terminal for repeatingsignals from the line to the subscribers loop circuit. The relay 8 may control printer apparatus if desired. For sending purposes a resistance network r 73 is provided connected to the loop circuit 7 and the outgoing circuit L The outgoing circuit L would com rise an oscillator 2 and an amplifier 3, as s own; When the telegrapii key 7, or printer transmitter, at the subscri rs ofiice is open a comparatively high ne ative otential'is applied from bat-- tery t roug the resistance network to the grid of the amplifier 3 and this stops the flow of carrier telegraph currentfrom oscillator 2 I to the line L When the telegraph key 7, or

printer, is closed positive potential from battery 9 in the-loop circuit is applied to the resistance network so as to bring the grid potential of the amplifier tube 3 to the proper valueas an amplifier and carrientelegraph.

current from oscillator 2 will be applied to the line L. This arrangement eliminates the p sending relay heretofore used at the carrier channel terminal for repeating signals from the subscribersloo to the line. The break relay usually'provi ed may also be eliminated as the arrangements of the invention provide an automatic break circuit due to the fact that opening key 7 in the loop circuit will send a telegraph system. These arrangements are substantially similar to those of Fig. 1 andsimilar reference characters have been used to denote like parts in both figures. In the full duplex system two separate loop circuits are provided. The receivmg loop 13 includes the key 16, relay 17, and

attery 19. The sending loop 12 includes the key 14, relay 15 and positive battery 18. The loop .12 is'connected to the resistance network r r as in Fig. 1. As the operation would be substantially the same as hereto described, no further description thereof, will be given.

In Fig. 3 the arrangements of the invention' are shown as ap lied to an intermediate repeater for a hal duplex telegraph system. An incoming lineL is shown including a receiving filter RF and an amplifier 39. The output of amplifier 39 is connected.

to the detector 32. and is also connected by conductor 40 to the grid of amplifier 24. The output of amplifier 24 is connected to a filter SF and thence to the outgoing line L... The grid of amplifier 24. is connected to the resistance network R R which in turn is connected to the loop circuit L and the output of detector 32 in a manner to be hereinafter described. An incoming line L is shown including a filter RF and an amplifier-28. The output of amplifier 28 is connected to a detector 29. The output of amplifier 28 is also connected by a conductor 41 to the grid of amplifier 43, the output of which is connected to the jfilter SF and thence to line L The grid of amplifier 43 'is also connected to the resistance network R R which is connected to the loop cir-.

33, 34 and 35, winding of relay cuit L and to the output of detectors 29 I and 32 which are connected in series.

The operation of the arrangements of Fig. 3 is as follows: When a marking signal 1s sent over lineL a carrier current flows over the line and through the amplifier 39. This carrier current will be applied to conductor and thence to'the id of amplifier 24 and thence out over. line The incoming carrier from line L will also be detected by detector 32 and transmitted over conductors 36, to battery 38. willo rate the re a or sounder 36 in the.-l oop The amp 'fier 24 will functlon because positive potential from battery 38 is ap lied over loop L to the resistance networ R R and neutralizes the blocking potential of battery 27. If the key '37 in the loop L is opened positivepotential e from battery 38 will be removed from both.

resistance networks R2; R2, and R R and bothamplifiers-24and 43 will be blocked.

'Thus a break signal may besent over lines L and L A marking signal sent over line L will be transmitted. through. amplifier 28 and applied over conductor 41 to the grid of amplifier tube 43 and thence transmitted out over line L 5 The signal coming in over line L will also be detected by detector 29 and transmitted over conductor 31,- I through detector 32, conductors 33, 34 and 35, winding of sounder 36 to battery 38 and will thus operate sounder 36. The circuit of loop L is traced as follo'ws: from negative battery 30, detector 29, conductor 31', detector 32, conductors 33, 34 and 35, relay 36, key 37 to positive battery 38. I

In Fig. 4 the arrangements of the invention are shown as applied to an intermediate repeater for a full duplex telegraph system. As' these arrangements are in many ways similar to those of Fig. 3 similar reference characters have been used to denote like parts with respect to Fig. 3. In Fig. 4 separate loop circuits are provided, such as L and L instead of a single loop circuit completed through both detector tubes in series ,as in Fig. 3. The loop L is completed as follows: from ground and battery 49, loop L key 47, sounder 44, loop L through detector 29 to ground. Positive potential may be applied from battery 49 and loop L when 47 is closed, over conductor to the resistance network R R This will neutralize or reduce the blocking potential from battery 42 and cause the. amplifier 43 to function assuch. The loop L is completed as follows:

. and cause the amphfier 24 .to' function as such.

The operation of the arrangements in other sirable, it is understood that they are capable v pended claims.

of embodiment'in many and other widely varied forms without departin from the spirit of the invention as define by the ap- What is claimed is:

1. A telegraph system comprising a transmission channel, an incoming circuit con: nected to said channel and including a detector, an outgoing circuit connected to said channel and including an amplifier and a source of signaling current connected to the input of said amplifier, a subscribers loo circuit directly connected to theoutput 0 said detector, means in said loop circuit responsive to the incoming detected signals, a resistance network connected to the grid of said amplifier, means for applying to said network a negative potential sufiicient to block said amplifier, means for connecting said resistance network to said loop clrcult, and a source of positive potential applied to said loop circuit suflicient to reduce the negative otential applied to the grid of said amplifier so as to unblock said amplifier.

2. A telegraph system comprising a transmission channel, an incoming circuitconnected to said channel and including a detector, an outgoing circuit connected to 'said channel and including an amplifier and a source of signaling current connected to the input of said amplifier, a subscribers loop circuit directly connected to the output of said detector, means in said loop circuit responsive to the incoming detected signals, a resistance network connected to the grid of said amplifier, means for apiiiplying to said grid a negative potential su cient to block said amplifier, means for connecting said re-' sistance network to said loop circult, means for applying a source of positive potential to said loop circuit suificient to reduce thev negative potential a plied to the grid of said amplifier so as to unblock said amplifier, and switching means for opening and closing said loop circuit between the connection to said resistance network and the point of application to said loop circuit of said source of positive potential.

3. In a telegraph system a repeater arrangement comprising incoming and outgoing transmission channels for transmission in one direction, incoming and outgoing fiers, means for connecting t transmission channels for transmission in the other direction, each of said incomin 'chan-- nels including receiving amplifiers an detectors, each of said outgoing channels includmg sending amplifiers, means for connecting the output of each receiving amplifier to the grids of corresponding'sending amplifiers,

a subscri-bers loop circuit connected to the output of said detectors, and means controlled by the operation of said loop circuit for con- Erolling the operation of said sending ampliers. Y

4. In a telegraph system a repeater arrangement comprising incoming and outgoing line sections for transmission in one direct1on,mcom1ng and outgom line sections for transmission 1n the other irectlon, each of said incoming line sections including receiving amplifiers and detectors, each of said outgoing line sections includin sending amplifie output of each receiving amplifier to the grids of corresponding sending amplifiers, a subscribers loop clrcuit connected to the output of said detectors, and means for applying difi'erent potentials to the grids of said sendlng amplifiers to render them operative or inoperative, 7

said last mentioned means being controlled by the operation of said loop circuit.

5. In a telegraph system a repeater arrangement comprising incoming and outgoing transmission channels for transmission 1n one direction, incoming and outgoing transmission channels for transmission in the other direction, each of said incoming channels including receiving amplifiers and detectors, each of said outgoing channels including sending amplifiers, means for connecting the output of each receiving amplifier to the grids of corresponding sending amplifiers, a subscribers loop circuit connected in series with both of said detectors, means in said loop circuit res onsive to the detected signals from either 0 said incoming lines,

resistance networks connected to the grids of each of said sending amplifiers, means for applying a relatively high negative potential to each of said networks to block said sending amplifiers, means for connecting said networks to said loop circuit, andmeans for applying to said loop circuit and said networks, a positive potential suflicient to reduce the negative potential applied to said networks tounblock said sending amplifiers.

6. In a telegraph system a repeater arrangement comprising incoming and outgoing transmission channels for transmission in one direction, incoming and outgoing transmission channels for transmission in the other direction, each of said incoming channels including receiving amplifiers and plifiers, subscribers loop circuits individual 1 I to each incoming line and connected to the detectors associated therewith means in each loop circuit responsive to the detected signals coming in over its corresponding line seetion, and se arate'means for up i? different tentia tothegridsofsai sen mgampli ers to control their operativeness, each of said last mentioned means being under the control of difi'erent ones of said 100 circuits. vIn testimony whereof, I have signed my name to this specification this 10th day of June, 1931. v

I BAXTER P. HALHLTON. 

